Browsing by Author "YAMAN, Vahide Selen"
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thesis.listelement.badge SYNTHESIS, CHARACTERIZATION AND INVESTIGATIONS OF THERMAL BEHAVIOR OF THE NITRO-IMIDAZOLE-BASED ENERGETIC COORDINATION COMPOUNDS(2022-06-16) YAMAN, Vahide Selen; ÖZALP YAMAN, Şeniz; EKİNCİ MACHIN, NesrinEnergetic materials produced in various structures have different applications both in the military as explosives and in the civilian field as propellant and pyrotechnics. However, due to the adverse effects of these materials on the environment and health as well as their high sensitivity to light and friction, it is desired to replace them with environmentally friendly, toxic metal-free and easy-handling alternatives. The main aim of this study is to synthesize and explore the performance of novel energetic organic and coordination compounds. In this scope, 5-(chloro(nitro)methyl)-4-nitro 1H-imizadole (HL) and its sodium (NaL) and ammonium (NH4L) salts were designed and synthesized as a first time. Next, totally 34 cobalt(II/III), copper(II), iron(II/III) and zinc(II) complexes containing 5-(chloro(nitro)methyl)-4-nitro-1H-imizadole were designed in octahedral and tetrahedral structures, [M(NH3)x(L)y] n [x:0, 2-4; y:1, 2, 4 or 6; n:(+1)-(-4)]. However, only 26 of these complexes could be synthesized successfully and characterized via various spectroscopic techniques (HRMS, NMR, FTIR). Especially, 6 L coordinated cobalt(II)/III) and iron(II)/III) complexes were found to be unstable due to the steric effect as it was also indicated by their optimized geometry calculations carried out as a part of the TUBITAK Project 117Z391 [1]. Thermo-gravimetric and differential thermal analyses (TGA-DSC) of these newly generated energetic coordination compounds were achieved and their thermal stability, thermal decomposition characteristics and kinetic parameters were determined to explore their potential to be used as an energetic material. The simultaneous TGA-DSC curves pointed out the similar decomposition processes with the high thermal stability within the range of 25-1200 oC for all the studied complexes. Among all these compounds; HL, NaL, NH4L and only five of the metal complexes showed exothermic behavior at around 800-1100 oC. It was observed that the exothermic decomposition temperature of the HL and its salts moved from 800 oC to 1100 oC upon coordination to the metal ions. It was very suprising that solely Co(II), Fe(II) and Cu(II) complexes including one or two L showed an exothermic character. Impact and friction sensitivity tests applied to the most promising two energetic compounds, [Co(NH3)4(L)2] and [Fe(NH3)4(L)2], revealed that these complexes were very resistant to impact and insensitive to friction. The agreement between the desired energy and sensitivity results indicated that our complexes can be applied as propellants in rocket systems and as additives in small amounts to modify the ballistic properties of propellants.